NEW YORK (AP) -- Auguste Rodin's "The Thinker" -- once a pensive fixture on the 105th floor of the World Trade Center -- has given investigators something to puzzle over. A 28-inch bronze cast of Rodin's most famous work fell to earth after terrorists slammed a jetliner into the north tower on Sept. 11. It turned up in the debris along with assorted remnants of other Rodins displayed in the offices of Cantor Fitzgerald bond trading firm. But the 19th century sculpture later disappeared, raising suspicions it was stolen. The city Department of Investigation refused to discuss reports that it is on the trail of "The Thinker." But a law enforcement official confirmed Monday that the piece apparently vanished after being recovered by a firefighter. The firefighter was questioned about a photograph of him posing with the sculpture, said the official, who spoke on condition of anonymity. The firefighter claimed he last saw it on Dec. 6 at the Fire Department's temporary headquarters at the disaster site. A call to a Fire Department spokesman was not immediately returned.

While still rare, several dozen casts of "The Thinker" are held by museums and private collectors around the world. Rodin often made a number of casts of his works for patrons, and the Musee Rodin in Paris has authorized limited castings of certain works. Cantor Fitzgerald representatives have declined to discuss the fate or value of the firm's art collection.

The firm lost 658 of its 960 World Trade Center employees in the attack. "The Thinker" -- whose disappearance was first reported earlier this month by The New York Post -- came from the Rodin collection of B. Gerald Cantor, once the world's largest. Cantor, who died in 1996, donated most of the works to museums and galleries, but left some on display in the lobby of Cantor Fitzgerald.

After Sept. 11, parts of some of the sculptures surfaced during the massive recovery effort in lower Manhattan. A bust from "The Burghers of Calais," and two headless figures from "The Three Shades" remain in FBI custody at Fresh Kills Landfill on Staten Island, where investigators have sifted through the rubble for human remains and criminal evidence.